Telephone-system receiver.



J. BRICKSON. TELEPHONE SYSTEM RECEIVER.

APPLICATION FILED MAB. 1, 1910.

' Patented Dec. 1, 191%,

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J. ERICKSON. TELEPHONE SYSTEM RECEIVER. APPLICATION EILED MAR. 1, 1910.I

Patented Dec. 1, 1914.

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, J. ERIG KSON. TELEPHONE SYSTEM RECEIVER.

APPLICATION FILED MAR-1,1910. 1, 1 18,926. Patented Dec. 1, 191% aSHEETS-SHEET s.

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JOHN ERICKSON, OF CHICAGO, ILLINOIS, ASSIGNOR TO'AUTOM ATIC ELECTRIQCOMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS. l

TELEPHONE-SYSTEM RECEIVER.

T 0 all whom it may concern:

citizen of the United States of America, andresiclent of Chicago, Cookcounty, Illinois,

have invented a certain new and useful Im provement in Telephone-SystemReceivers, of which the following is a specification.

invention relates to telephone receivers of thekind in whichelectromagnets are employed.

Prior to my invention the cores of the electromagnets of telephonereceivers had been made of solid iron, with the result that eddycurrents would develop therein, causing some, loss of eliiciency.

My invention contemplates, therefore, a telephone receiver in which theelectro magnet thereof has a laminated core, which core may consist of aplurality of flat plates laid together, or a plurality of wires heldtogether in the form of a bundle, said plates orwires being preferablyof soft iron.

These plates or wires may be suitably insulated from each other ifdesired. or the superfi ial oxidation of the iron which invariably takesplaces may be depended ,upon to furnish the resistance necessary tobreak up the eddy currents, as will hereinafter more fully appear.

For the broader purposes of my invention the receiver may be of anysuitable, known or approved character. I find, however. that myimprovement, which consists in using laminated cores for theelectroniagiiets of telephone receivers, is especially beneficial forthat form of receiver in which the coil or coils thereof are connectedin series with the line and in which battery current is supplied overthe line circuit to the coil or coils of the receiver, whereby nopermancn't or polarizing niagnet is necessary.

To the foregoing and other useful ends my invention consists in mattershereinafter set forth and claimed.

In the accompanying drawings Figure 1 is a longitudinal section of areceiver embod ving the principles of my invention.

Fig. 2 is an end elevation or face View of the receiver shown in Fig. 1,with the diaphragm thereof removed. Fig. 3 is a detail view of themounting or connection-fitting by which the circuit conductors areconnected with the coils of the receiver. Fig. 4: is a diagram of atelephone circuit illustrating the manner in which my improvedSpecification of Letters Patent.

Patented Dec. 1,1914.

Application filed March 1, 1910. Serial No. 546,614.

receiver may be connected in the line in series with the transmitter ina common battery system. Figs. 5 and 8 are longitudinal sections ofreceivers embodying additional features of my invention. Figs. 6 and 9are end elevations of the receivers shown iin F gs. 5 and 8,respectively, with the cap and d aphragm removed. Figs. 7 and 10 arediagrams of telephone circuits illustrating the manner in which thereceiversshown in l1 1 gs. 5 and 8, respectively, may be connected inthe line in series with the transmitter in a common battery system. i

As illustrated in Figs. 1 and 2, my receiver comprises the usual casingA and the screw-threaded cap or centrally-apertmed cover B. In the loweror enlarged end of the casing A is secured a flanged dup C preferablycomposed of brass or some other nonmagnetic material. The flange 0' ofthe cup C is adapted to extend over the end of the wall of the casing A,and the cup G and diaphragm D are clamped in place thereon by the capll. Inside the cup C there is re cured an electromagnet E comprising acoil of wire e and a core 6 The core 6 is U- shaped and is composed of anumber of small iron wires. The ends of the core are clamped between twobars 1' and f which are composed of brass or other non-magneticmaterial. The ends of the bars f and f are secured to the walls of thecup C by means of screws 7' to hold the electroinagnetE in position withthe ends of the cores a slight distance back of the diaphragm. The polesof the elcctroniagnet E are thus secured diametrically opposite eachother and equidis-- tant from the center of the diaphragm D.

(Fig. 2) which project through openings .in 100 the back of the cup Cand to which the terminals of the coil 6 are connected. Thebindingsposts 9 and provide means by which the receiver cord 9 may be connectedwith the coil of the electromagnet E. The i terminal plugs 9 and of thereceiver cord are clamped in the binding posts 9 and g" by the screws 1and 9. To the terminal block G'there is also secured a. hook or ring g".The receiver cord 9 is attached to the 110 hooky by the cord g, wherebythe weight of the receiver may be sustained by said cord 9 and not bythe terminal plugs g and 9 Referring to big. 4 it will be seen that thereceivers are here shown diagrammati- .cally and that the electromagnetsE are connected in series with the transmitters in a common batterysystem. As shown, the current from the central battery I is suppliedover the line circuit and passes to the transmitters and receivers atthe substations, whereby as soon as the line circuit is closed thediaphragnis of the receivers are placed under a stress or tension as aresult of the energizing of the electromagnets of the said receiver. Inthis way no permanent magnets are necessary for the receivers, as boththe battery and voice-currents traverse the windings by which thediaphragms of the receivers are actuated. Since the core is composed ofa number 01" wires the injurious effects of eddy currents which arepresent in solid cores are greatly reduced.

The receiver shown in Figs. 5 and 6 is similar to that shown in Figs. 1and 2 with the exception of the electromagnet J. The core of theelectromagnet J is composed of a number of iron wires and is W-shaped.All of the wires extend through the center of the coil j to form acentral pole j while half of the wires are bent up on either side of thecoil to form two other poles i and j.

The electromagnet j thus has three poles,

the cross-section of the. central one (j be-- ing equal to the sum ofthe cross-section of the two outer poles j and j The electromagnet isheld in position by the cross bars 7' and j which are attached to theWalls of the cup K by means of screws. In the form of the receiver shownin Figs: 8 and 9 the core of the electromagnet L is formed of two flatstrips oi iron bent into U-shape. One limb of each of the Us extendsthrough. the center of the coil, while the other limbs extend up on theoutside of. the coil on opposite sides of the center. \Vith thisarrangement an electroinagnet is obtained which has three poles, thecenter one of which has double the cross-section of either one of theouter poles and is split or divided into two parts. The electromagnct Lis held in position by two screws Z which pass through the back of'thecup l into the cores Z" and Z From the foregoing it will be seen that myinvention, broadly considered, is a telephone receiver provided with anelectromagnct having a laminated core or polepiece. More specificallyconsidered my invention is in the nature of a telephone receiver inwhich no permanent magnet is em- I ployed, and in which the core of themagnet that receives the battery current is lami-' nated in any suitablemanner, as by using either plates or wires, in the manner previouslyexplained. As shown in the drawings, the different parts of thelaminated core are not insulated from each other by any special orartificial insulation. This may be done if desired, but I 11nd that forall practical purposes the superficial oxidation of the soft iron may bedepended uponto interrupt or break up the eddy currents,

and that sufiicient resistance or lnsulation may be obtained in thismanner. This is particularly true when the laminated core is composed ofa bundle of wires, as in such case the surface of each Wire becomesoxidized and the resistance between the wires becomes amply sufiicientto destroy, or at least materially reduce, the eddy currents whichresult from the passage of voice-currents through the winding of themagnet.

\Vhat 1. claim as my invention is 1. A telephone receiver comprising 2.diaphragm, and an electromagn'et core,said

core comprising a pair of U-shaped members,

a pair of adjacent U-shaped-mmhers, each composed of a bundle of softlrenwires, the ends oi said members being adjacent to but out oi contactwith said diaphragm, a cup inclosing said core, and a pair ofnon-magnetic bars clamping the ends of-said core .to each cup.

8. A telephone receiver comprising a diaphragm, an electromagnetcorecomposed of U-shaped laminations, the ends of said core being adjacentto but out of contact with said diaphragm, a cup inclosing said core,and clamping membersffor securing the ends of said core to said cup.

Signed by me at Chicago, Cook county. Illinois, this 10th day of F ch,1910.

JOHN ERIOKSON. J I Witnesses EDWARD D. FALEs, ARTHUR J. RAY.

